Non-Venomous Snakes


Though non-venomous snakes pose little danger to humans, you should still give them their space. These snakes play a vital role in the ecosystem by eating insects and small mammals.

Read more about our venomous snakes. Our park species list has a complete list of snakes and other species found in the Big Thicket.

close up of a rough green snake
Rough green snake

NPS Photo / Scott Sharaga

Rough Green Snake

Opheodrys aestivus

Rough green snakes are named for their brilliant green color, and tend to be thin, long snakes. They can grow to be over two feet long.

Rough green snakes can be found throughout the Southeastern United States. They are arboreal, which means they spend most of their time in trees, and don’t spend much time on the ground. They hunt in the trees, consuming mostly small invertebrates such as crickets, spiders, and moths. These snakes are most active during the day, and are therefore more commonly seen than nocturnal snakes. But, they can be difficult to spot because they spend most of their time in the leaves of trees, where their bright green scales blend in perfectly.

Rough green snakes will lay clutches of eggs in leaf litter or in hollows in the ground in late spring and early summer. They usually lay four to six eggs, but in years where food is abundant they can lay more. The young snakes are about eight inches when they hatch, and are able to start eating small insects right away.

person holding a red/black/white milk snake
A park researcher holds a milk snake

NPS Photo / Herbert Young

Milk Snake

Lampropeltis triangulum

There are a few different subspecies of milk snake, but most have bright black, red, and white banding along their bodies. Milk snakes are nocturnal and are most commonly seen on the ground. Like all snakes, milk snakes are primarily carnivorous and eat a variety of small animals. These snakes are opportunistic eaters that will eat anything from insects to rodents.

Milk snakes are not generally aggressive snakes, and are not likely to attack. However, milk snakes are known for looking similar to coral snakes, which are venomous and very dangerous. They can be differentiated by the yellow bands on coral snakes which always touch the red bands on the snake’s back, whereas milk snakes always have black bands next to red bands (“red on black friend of jack, black on yellow kills a fellow”).

Milk snakes mate in early summer and lay eggs in midsummer (June to July). The size of clutches can vary a lot, but have an average of about six eggs. The eggs hatch in early fall. During the winter snakes will brumate (which is similar to hibernation) in underground pits. Milk snakes will sometimes share these pits with other snakes that brumate such as copperheads.

close up of a garter snake among leaves
Garter snake. Notice the black stripes beneath the eye, a characteristic of garter snakes. (Photo from Catoctin Mountain Park, Maryland)

NPS Photo / Alicia Lafever

Common Garter Snake and Western Ribbon Snake

Thamnophis sirtalis and Thamnophis proximus

These two snakes are both found in the Big Thicket region, and can be very tricky to tell apart! Both are relatively harmless to humans, so mistaking one for the other isn’t going to result in a dangerous snake bite. Both snakes are members of the Thamnophis genus, which is the genus that makes up the various species of garter snake. Both of these snakes are usually about two feet long but can grow up to four feet in length. These snakes eat small lizards, amphibians, and small invertebrates.

Ribbon snakes are dark with three long light colored strips running the length of their bodies. Garter snakes can be more varied in appearance, but can also have the exact same dark coloration with three long stripes running down their body. However, there are a few key differences that can be more reliably used to tell the difference between the two.

close up of ribbon snake among dead leaves
Ribbon snake

NPS Photo / Andrew Bennett

  • Ribbon snakes always have a white bar just in front of their eyes. Some common garter snakes may have a white patch in front of their eyes, but it won’t be clearly defined the way a ribbon snake's eye spot is. Look at the pictured ribbon snake and compare the white bar in front of it’s eye to the white patch in front of the common garter snake’s eye.
  • Another reliable difference is the scales along the lower jaw. Both snakes have lighter colored lower jaws, but a ribbon snake's lower jaw scales will be completely white. Common garter snakes' scales on their lower jaws will have darker edges instead of being completely white.

Ribbon snakes also tend to be thinner than common garter snakes, and have narrower heads. However, these differences are hard to use unless you have a ribbon snake and common garter snake right next to each other!

Fitch, H. S., & Fleet, R. R. (1970). Natural history of the milk snake (Lampropeltis triangulum) in northeastern Kansas. Herpetologica, 387-396.

Goldsmith, S. K. (1984). Aspects of the natural history of the rough green snake, Opheodrys aestivus (Colubridae). The Southwestern Naturalist, 445-452.

Hamilton, B. T., Hart, R., & Sites, J. W. (2012). Feeding ecology of the Milksnake (Lampropeltis triangulum, Colubridae) in the western United States. Journal of Herpetology, 46(4), 515-522.

Pfennig, D. W., Harper, G. R., Brumo, A. F., Harcombe, W. R., & Pfennig, K. S. (2007). Population differences in predation on Batesian mimics in allopatry with their model: selection against mimics is strongest when they are common. Behavioral Ecology and Sociobiology, 61(4), 505-511.

Vest, D. K. (1981). The toxic Duvernoy's secretion of the wandering garter snake, Thamnophis elegans vagrans. Toxicon, 19(6), 831-839.

Werler, J. E., & Dixon, J. R. (2010). Texas snakes: identification, distribution, and natural history. University of Texas Press.

Williams, B. L., Brodie Jr, E. D., & Brodie III, E. D. (2003). Coevolution of deadly toxins and predator resistance: Self-assessment of resistance by garter snakes leads to behavioral rejection of toxic newt prey. Herpetologica, 59(2), 155-163.

Williams, B. L., & Brodie, E. D. (2004). A resistant predator and its toxic prey: persistence of newt toxin leads to poisonous (not venomous) snakes. Journal of chemical ecology, 30(10), 1901-1919.

Last updated: December 23, 2023

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